Production of asphalt



Patented Nov. 5, 1940 UNITED STATES 2,220,714 rnonuc'rrou or ASPHALT Arthur B. Hcrsberger, Philadelphia, Pa., assignmto The Atlantic Refining Company,'Philadelphia, Pa., a corporation of Pennsylvania No Drawing. Application June 14, 1938,

- Serial No. 213,623

9Claims.

The present invention relates to the treatment of bituminous materials, and particularly bituminous materials, such as cracked or uncracked petroleum residuum. A principal object of this invention is the pro-v duction of improved asphalts from bituminous residues, and particularly from petroleum residuum containing about or less by weight of asphaltenes, which will not yield homogeneous asphalts when treated according to conventional methods.

A further object of this invention is the production of homogeneous asphalts having a negative Oliensis test from domestic crude petroleum residuum having a relatively low content ofasphaltenes. Such test is desecribed in A.S.T.M. Proceedings, part II, vol. 39 (1936), page 506 et seq., and is being widely adopted in asphalt specifications as an index of homogeneity of asphalt products.

A further object of this invention is the treatment of residuums produced by the cracking or non-cracking distillation of petroleum; residues from the hydrogenation of petroleum; heavy residual oils produced by polymerization; and residues produced by the treatment of petroleum oils with selective solvents or with asphalt-precipitating agents such as petroleum naphtha, pentane, butane, propane, ethane and the like.

In the production of asphalts, it has heretofore been customary to subject asphaltic crude oils to fire and steam distillation whereby volatile oils are removed, leaving an asphaltic residuum, or to subject the asphaltic residuum so produced to oxidation with air at elevated temperatures to yield asphalts of increased softening point. However, it has been found impossible to produce from petroleum residuums containing less than about 10% by weight of asphaltenes, satisfactory asphalts exhibiting a negative Oliensis test, by air oxidation, distillation or blending, or combination of such steps.

I have found that by treating bituminous materials, and particularly petroleum residuum, with sulfur and air or oxygen-containing gas at elevated temperatures such that reaction of the sulfur and air with the petroleum residuum is effected, I am able to obtain asphaltic materials of markedly increased softening point.

Furthermore, in accordance with my invention I am able to produce homogeneous asphalts, as indicated by a negative Oliensistest, from petroleum residuums which will not, produce such asphalts when processed in theconventional manner. In other words, petroleum residuums which cannot be converted into homogeneous asphalts by conventional distillation, air blowing, and blending or combination of such steps are amenable to my treatment and will yield homogeneous asphalts of the character of those derived 5 from asphaltic crude oils such as Mexican and Venezuelan.

In carrying out my invention, a bituminous material such as a crude petroleum residuum is subjected to the action of sulfur, in the presence 10 of an oxygen-containing gas such as air, at elevated temperatures of the order of from about 300 F. to about 550 F. for a period of time varying from about hour to about 8 to 10 hours or more, depending upon the rate of reaction be- 15 tween the sulfur and. air and the petroleum residuum. The quantity of sulfur employed may vary from about 0.5% to about 5% by weight, and is preferably of the order of from about 1% to about 3% by weight of the residuum treated. In general, upwards of 95% of the quantity of sulfur brought into contact with the petroleum residuum is caused to react therewith.

Treatment of the residuum may be effected at substantially atmospheric pressure by simply blowing an oxygen-containing gas, such as air, through a mass of the residuum containing added sulfur at elevated temperatures, or the sulfur may be admixed with the residuum and treated with air at elevated temperatures and under a 3 substantial superatmospheric pressure of the order of -100 lbs/sq. in. or higher. In one modification of my process, air may be passed through a pool or series of pools of petroleum residuum containing added sulfur maintained at a temperature of the order of from about 300 F. to about 550 F., or the air may be diluted with nitrogen, carbon dioxide or flue gas and brought into contact with the heated residuum containing added sulfur. Or, alternatively, heated residuum containing added sulfur may be sprayed or flowed downwardly through a tower in intimate countercurrent contact with an oxygen-containing gas such as air. Air containing sulfur gases from the contacting step may be recirculated to 5 said contacting step, if desired.

In accordance wtih my invention, I may treat the so-called non-asphaltic" petroleum residues containing relatively small amounts of asphaltenes, i. e., less than about 10% by weight of asphaltenes, such as are derived from Texas and Oklahoma or other non-asphaltic crudes, with sulfur andian oxygen-containing gas at elevated temperatures to produce asphaltic materials of improved characteristics. Such materials, when subjected to further treatment involving distillation and blending with oils or residues of different nature, preferably those rich in resins, i. e., containing 30% to 50% or more, of resins, will produce homogeneous asphalts of the general character of those derived from the true asphaltic crude oils of Mexico and Venezuela. Petroleum residual oils, such as those resulting from the distillation of Texas, Oklahoma or other non-asphalt base crudes, cannot be converted into asphalts having a negative Oliensis test and the characteristics of Mexican or Venezuelan asphalts by merely blowing with air at elevated temperatures and distilling and blending the -air-blown products with other oils or residues.

The principal advantage of my process is the ability to produce, from domestic crude petroleum or petroleum deficient in asphaltenes, specification asphalts which are more homogeneous, as measured by the Oliensis test, than asphalts produced from the same residuum by conventional methods of air oxidation, distillation and/or blending. A negative Oliensis test indicates a homogeneous asphalt, while a positive test indicates a non-homogeneous asphalt.

My invention may be illustrated by the following examples, which are not to be construed as limiting the scope thereof.

(1) A crude petroleum residuum (17% bottoms from West Texas crude oil) having a Saybolt Universal viscosity of 839 seconds at 210 F., an A. P. I. gravity 12.5", a flash point of 560 F., a fire point of 640 F., and comprising 52.5% oil, 44.0%

resins, and 3.5% asphaltenes was blown with air,

in the absence of added sulfur, at a temperature of 400 F. for a period of 4 hours, air being supplied at a rate of 2.1 cubic feet/hour/gallon of residuum. As a. result of such treatment there was produced an asphaltic material having a softening point of 124 F., and a positive Oliensis test, which indicated the material to be non-homogeneous. The treated asphaltic material, when blended with untreated residuum in the ratio of 62 parts by weight to 28 parts by weight, yielded a non-homogeneous asphalt having a positive Oliensis test.

A quantity of the same untreated residuum as employed above, to which had been added 2% by weight of sulfur, was blown with air under the conditions as described above, and there was produced an asphaltic material having a softening point of 124 F., and a negative Oliensis test, which indicated the material to be homogeneous, This asphaltic material was then reduced to 150 F. softening point byvacuum distillation, and the 150 F, softening point residue was blended in the 'ratio of 62 parts by weight to 38 parts by weight with the initial, untreated residuum. The resulting blended asphalt had a softening point of 117 F., and a negative Oliensis test, indicating that the blended material was homogeneous. The other properties of this asphalt were substantially the same as those of an asphalt produced by fire and steam distillation of a Venezuelan crude oil.

(2) A quantity of the untreated residuum of Example 1, to which had been added 1% by weight of sulfur, was blown with air at a temperature of 400 F. for a period of 3 hours, air being supplied at a rate of 2.1 cubic feet/hour/gallon of residuum. As a-result of such treatment there was produced an asphaltic material having a softening point of 120 F., and a negative Oliensis test, This as-- phaltic material was blended in the ratio of 62 parts by weight to 38 parts by weight with the initial, untreated residuum, and the blend d material was then reduced by vacuum distillation, about 25% of volatile oils being removed. The resulting asphalt had a softening point of 115 F, and a negative Oliensis test. This asphalt also corresponded to a Venezuelan asphalt oi the same softening point.

(3) A naphthenic residual oil, produced by nitrobenzene extraction of West Texas crude residuum, having a Saybolt Universal viscosity of 1692 seconds at 210 F. and an A. P. I. gravity of 9.3", was admixed with 1.75% by weight of sulfur and the mixture was blown with aifat a; temperature of 400 F. for a period of 3 /2 hours, air being supplied at a rate of 2.1 cubic feet/hour/gallon of residual oil. There was produced, as a result of such treatment, an asphaltic material having a. softening point of 126 F., and a negative Oliensis test. This asphaltic material was then blended in the ratio of 85 parts by weight to 15 parts by weight of the initial, untreated residual oil and there resulted an asphalt having a softening point of 118 F., and a. negative Oliensis test, said asphalt being similar in other properties to a Venezuelan asphalt of the same softening point.

(4) A quantity of the same untreated petroleum residuum as employed in Example 1 was admixed with 1% by weight of sulfur and the mixture was heated at a temperature of 450 F. under air pressure of 95'lbs./sq. in. for a period of 2 hours. As a; result of such treatment there was produced an asphalt having a. softening point of 148 F., and a negative Oliensis test.

The same petroleum residuum, when treated under the same conditions, but in the absence of added sulfur, yielded an asphaltic material having a. softening point of 144 F., and a positive Oliensis test.

It will be seen from the above examples, that treatment of petroleum residuum at elevated temperatures with air and sulfur produces asphaltic materials having a negative Oliensis test, which materials, when blended with residuum rich in resins, yield asphalts homogeneous in character, as evidenced by the negative Oliensis test. On the other hand, the same residuum, when merely air blown at elevated temperatures but in the absence of added sulfur, yields asphaltic material which is non-homogeneous according to the Oliensis test. By my process involving treatment of petroleum residuum poor in asphaltenes with air and sulfur at elevated temperatures, followed by distillation and/or blending with heavy oils rich in resins, there may be produced homogeneous asphalts having the general characteristics of steam refined Mexican or Venezuelan asphalts, whereas such treatment in the absence of added sulfur will not produce the desired asphalts.

What I claim is:

1. The method of producing asphalt from petroleum residual oil containing less than about 10% of asphaltenes, which comprises contacting said residual oil with sulfur and free-oxygen con,- taining gas at an elevated temperature such that reaction of the sulfur and free-oxygen containing gas with the residual oil is effected, and blending the treated residual oil with high boiling hydrocarbon oil rich in resins.

2. The method of troleum residual oil containing less than about 10% of asphaltenes, which comprises contacting said residual oil with sulfur and free-oxygen containing gas at an elevated temperature such that reaction of the sulfur and free-oxygen containing gas with the residual oil is effected, removing from .the treated residual oil volatile oils, and blending producing asphalt from pe-' troleum residual 011 containing less than about 10% of asphaltenes, which comprises contacting said residual oil with from about 1% to about 3% by weight of sulfur and free-oxygen containing gas at a temperature of from about 300 F. to about 550 F. to cause reaction of the sulfur and free-oxygen containing gas with the residual oil,

removing from the treated residual oil volatile oils, and blending the residue with high boiling hydrocarbon oil rich in resins.

5. The method of producing asphalt having a negative Oliensis test from petroleum residual oil containing less than about 10% of asphaltenes, which comprises contacting said residual oil with sulfur and air at an elevated temperature such that reaction of the sulfur and air with the residual oil is eflected, and blending the treated residual oil with high boiling hydrocarbon oil rich in resins.

6. The method of producing asphalt having a negative Oliensis test from petroleum residual oil containing less than about 10% of asphaltenes, which comprises contacting said residual oil with sulfur and air at an elevated temperature such that reaction of the sulfur and air with the residual oil is effected, removing from the treated residual oil volatile oils, and blending the residue with high boiling hydrocarbon oil rich in resins.

7. The method of producing asphalt having a negative Oliensis test from petroleum residual oil containing less than about 10% of asphaltenes, which comprises contacting said residual oil with sulfur and air at a temperature of from about 300 F. to about 550 F. to cause reaction of the sulfur and air with the residual oil, removing from the treated residual oil volatile oils, and blending the residue with high boiling hydrocarbon oil rich in resins.

8. The method of producing asphalt having a negative Oliensis test from petroleum residual oil containing less than about 10% of asphaltenes, which comprises contacting said residual oil with from about 1% to about 3% by weight of sulfur and air at a temperature of from about 300 F. to about 550 F. to cause reaction of the sulfur and air with the residual oil, removing from the treated residual oil volatile oils, and blending the residue with high boiling hydrocarbon oil rich in resins.

9. The method of producing asphalt from petroleum residual oil containing less than about 10% of asphaltenes, which comprises contacting said residual oil with sulfur and air at a temperature of from about 300 F. to about 550 F. to cause reaction of the sulfur and air with the residual oil, blending with said treated residual oil a quantity of oil rich in resins, and removing volatile oils from the blended material by dis- 35 tillation.

AR'I'HUR B. HERSBERGER. 

